Litronix 2290

If there had been an award given for the least functional programmable calculator ever made, the Litronix 2290 would have been a strong contender. Imagine: a basic, four-function calculator with square root (hit ÷+=) and percent, a single memory register, and room for 10 program steps! It makes me wonder why its designers bothered with programmability at all.

The 2290's programming model is somewhat unusual. Like many of the earliest programmables (e.g., the Novus 4525 from National Instruments) it provides no capability for viewing or editing programs. It simply memorizes your keystrokes, that's all. However, unlike other programmables, the 2290 only memorizes operator keys; when numeric keys are used, for instance, they are interpreted as a halt instruction, causing the calculator to wait for user input.

This is demonstrated by the example shown on the calculator's back label. You can key in a program sequence to multiply two numbers as follows:

C/ONL2×3+=S

To play back the program, you'd then type

10E5E

and the calculator displays 50, the product of 10 and 5. (Incidentally, this also means that it is impossible to store a constant value in a program.)

With 10 programming steps and 4 functions, it is rather difficult to conceive a program that's even remotely meaningful. Certainly no way to implement the Gamma function, the factorial, or even Stirling's formula on this beast! Instead, here's a simple exercise from Newtonian physics, calculating the amount of time it takes for an object to fall from a given height. Storing the gravitational acceleration (9.81 m/s² at sea level) in the calculator's memory, you can key in the following program:

C/ONL+=+=÷RM÷+=S

To calculate, for instance, the number of seconds it takes to fall from a height of 100 meters, type 100E (the result is 4.52 seconds. Not a heck of a lot to say your prayers if you happen to jump out a window on the 30th floor.)